My issued patent and my prior copending application disclose a powered hand-held rotary driver having an internal mechanism for minimizing the externally manifested reaction torque that will be imposed upon the hand of the operator. The tool includes a housing, a rotor supported for rotation relative to the housing, and a planetary differential mechanism having a sun gear, planetary gears, and a ring gear. The sun gear is coaxial with the rotor. The tool is characterized by the fact that the ring gear, rather than being fixed to the housing, is supported for rotation relative to the housing.
An output gear is coaxial with the sun gear and is rotatably driven by the cage of the planetary gears. A shaft is supported from the housing on an axis that is laterally offset from the axis of the rotor. The ring gear drivingly engages the laterally offset shaft, and a rotation inhibitor is attached to the offset shaft. The rotation inhibitor in my prior patent was operable for only one particular direction of rotation.
The embodiment shown in my issued patent and copending application also included concentric output shafts for use with a particular type of fastener.
There is also a need, however, to reduce the reaction torque in reversible hand-held rotary tools having only a single output. Some examples of that type of tool include powered nut drivers for attaching wheels to automobiles, and other purposes; powered screw drivers; and the like.